The present application relates to talc slurries that exhibit minimal foaming.
Talc is a mineral used in the paper making and coating arts. More specifically, talc has been used as a filler in base sheets, and as a pigment in enamel coating of papers. It is advantageous to the paper maker to receive talc in the form of a pumpable, aqueous slurry, in that it greatly simplifies the handling of the mineral.
In conventional practice the mineral processor mines the talc and suspends it in water. Talc pigment is highly hydrophobic with a surface energy of 68-70 j/cm.sup.2. This low surface energy makes talc difficult to disperse in water. Relatively large amounts of nonionic polymers must be used as wetting agents in combination with other dispersing agents to adequately disperse the talc. The relatively large amounts of these surface active agents present in the talc slurry disadvantageously lead to excessive foaming of the slurry. Foaming clogs screening, coating application mechanisms, and otherwise makes the handling of the slurry very difficult and impractical.
Accordingly, there is an unresolved need for a talc slurry that does not foam excessively.